Supporting system in exposure apparatus

ABSTRACT

Disclosed is a supporting system having a carrying member for carrying a workpiece thereon and a supporting mechanism for supporting the carrying member from a workpiece transfer position to a workpiece processing position, wherein, adjacent the transfer position, the weight of the carrying member and a force to be applied to the carrying member are substantially balanced, and wherein, adjacent the workpiece processing position, the weight of the carrying member and a force to be applied to the carrying member are substantially balanced.

FIELD OF THE INVENTION AND RELATED ART

This invention relates to a supporting system suitably usable, forexample, in a fine-motion stage of a wafer stage incorporated into asemiconductor exposure apparatus.

FIG. 28 is a perspective view of a wafer rough-motion stage of asupporting system used in a semiconductor exposure apparatus. In thiswafer rough-motion stage, a Y yaw guide 202 is fixed on a base table201, and a Y stage 203 which is guided by a side face of the Y yaw guide202 and a top face of the base table 201 is slidably supported on thebase table 201 by means of an air slide (not shown) along a Y direction.The Y stage 203 consists mainly of four components, that is, two X yawguides 204, a Y large slider 205 and a Y small slider 206. The Y largeslider 205 is opposed to the side face of the Y yaw guide 202 and thetop face of the base table 201, through air pads (not shown) provided atthe side and bottom faces thereof. The Y small slider 206 is opposed tothe top face of the base table 201 through air pads (not shown) providedat the side face thereof. With this structure, the Y stage 203 as awhole is supported on the top face of the base table 201 and the sideface of the Y yaw guide 202, slidably in the Y direction.

On the other hand, an X stage 210 is guided by the top face of the basetable 201 and the side faces of the two X yaw guide 204 which arecomponents of the Y stage 203. The X stage 210 is provided so as tosurround the X yaw guide 204 of the Y stage 203, around the X axis. TheX stage 210 is supported slidably, in the X direction, by means of anair slide (not shown). The X stage 210 consists mainly of forcomponents, that is, two X stage side plates 211, an X stage top plate212 at the top end, and an X stage bottom plate 213. The bottom plate213 is opposed to the top face of the base table 201 through air pads(not shown) which are provided at the bottom face of the bottom plate.The two X stage side plates 211 are opposed to the side faces of the twoX yaw guides 204, which are components of the Y stage 203, through airpads (not shown) provided at the side faces of the side plates. Thebottom face of the X stage top plate 212 and the top face of the X yawguide 204, as well as the top face of the X stage bottom plate 213 andthe bottom face of the X yaw guide 204 are kept out of contact with eachother. With this structure, the X stage 210 as a whole is supported atthe side faces of the two X yaw guides 204 and the top face of the basetable 201, slidably in the X direction.

As regards the driving mechanism, there are multiple-phase coilswitching type linear motors 214 and 215, one for X driving and two forY driving. A stator 216 comprises a plurality of coils 217 arrayed inthe stroke direction and being inserted into a frame 218. Amovable-element 219 comprises a magnet unit of box shape. In accordancewith the position of the movable element 219, electric currents areselectively applied to coils 217 of the stator 216, whereby a thrust isproduced. Mounted on the top of the X stage top plate 212 is afine-motion stage 221 shown in FIGS. 29 and 30.

The fine-motion stage 221 serves to position a wafer W (workpiece)placed on the X stage top plate 212, with respect to Z tilt and θdirection. By means of three Z suspension driving units 222-1 to 222-3provided at the peripheral portion, the wafer stage top plate 223 issupported and positioned with respect to Z tilt direction. A universaljoint 224 provided at the central portion serves to confine the freedomto prevent shift of the wafer stage top plate 223 in X and Y directions.

The Z suspension driving units 222-1 to 222-3 each comprises an aircylinder 226 for supporting the weight of the wafer stage top plate 223,and a Z linear motor 230 for applying a force, in the Z direction, tothe wafer stage top plate 223.

The Z linear motor 230 comprises a flat coil 231 having a major orlengthwise side parallel to a horizontal line, four magnets 232 opposed,through a gap, to the major side of the flat coil 231, and two yokes 233for circulating the magnetic flux of the magnets 232. The flat coil 231is fixed to the X stage top plate 212, and the magnets 232 and the yokes233 are fixed as a unit to the wafer stage top plate 223. As an electriccurrent is applied to the flat coil 231, a force in the Z directionoperates between the coil 231 and the integral structure of the magnet232 and the yoke 233.

The air cylinder 226 comprises a supporting rod 227 and a rubber film228. The rubber film 228 is provided at the lower portion of the waferstage top plate 223, and it serves to define an air chamber 229 betweenthe lower portion of the top plate 223 and the supporting rod 227. Airsare supplied through a supply port, not shown. The supporting rod 227has an end fixed to the flat coil 231, and the other end is coupled tothe rubber film 228. As a result, the weight of the wafer stage topplate 223 is supported from the X stage 210 and through the flat coil231, the supporting rod 227 and the air chamber 229. The air chamber 229provides a soft spring in the Z direction, so that vibration in the Zdirection can be substantially blocked.

The Z linear motor 230 does not bear the function of weight support butit operates solely for the position control. With this structure, anelectric current which may otherwise cause a problem of heat generationis not flown thereto.

The universal joint 224 comprises an outer ring 236 fixed to the X stagetop plate 212, an inner ring 237 fixed to the wafer stage top plate 223,and a guide 238 for slidably guiding the outer and inner rings 236 and237. The guide 238 may comprise an air guide, for example, having an airgap of a few microns. This air gap has a ring-like shape, and the innerring 237 and the outer ring 236 as well as the X stage top plate 212 andthe wafer stage top plate 223 are guided for slidable motion along the Zand θ directions. The height of the guide 238 in the Z direction is setlower, such that motion of the inner and outer rings 234 and 236 as wellas the top plates 212 and 223 in the tilt direction is allowed.

Although not shown in the drawings, a mechanism similar to the Z linearmotor 230, including a flat coil 231 having a major or lengthwise sideparallel to the vertical line, is provided, so that the wafer stage topplate 223 can be moved in the θ direction.

Mounted on the side face of the wafer stage top plate 223 is a squaremirror (not shown) which enables precision measurement of the position,in six-axis direction, of the wafer stage top plate 223 by use of alaser interferometer.

In the structure described above, in conventional exposure apparatuses,a wafer W is precisely positioned with respect to the X, Y, Z, θ andtilt directions, by means of a control system (not shown) and byapplying appropriate electric control to coils of rough-motion X,rough-motion Y, fine-motion Z1, fine-motion Z2, fine-motion Z3 andfine-motion θ. Then, an exposure process is performed by using exposuremeans (not shown), whereby a pattern of an original (not shown) issequentially printed on a wafer W.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, there is provideda supporting system, comprising: a carrying member for carrying thereona workpiece; and a supporting mechanism having a magnet, for supportinga weight of said carrying member; wherein a supporting force to beprovided by said magnet does not change with a shift of said carryingmember along a plane perpendicular to a direction in which the weight issupported.

The supporting mechanism may have a magnet and a magnetic member,wherein said magnet and said magnetic member may differ from each otherin respect to a size in a direction perpendicular to a direction inwhich a force operates between said magnet and said magnetic member.

The supporting mechanism may include plural magnets for mutuallyoperating a force, wherein one magnet differs from another magnet inrespect to a size in a direction perpendicular to a direction in which aforce operates between the magnets.

The supporting mechanism may include a magnetic member and anelectromagnet, wherein said magnetic member and said electromagnet maydiffer from each other in respect to a size in a direction perpendicularto a direction in which a force operates between said magnetic memberand said electromagnet.

Each of said magnetic member and said electromagnet may comprise alayered structure of thin magnetic material plates.

There may be a controller for controlling an electric current to saidelectromagnet.

There may be a detector for detecting a clearance between saidelectromagnet and said magnetic member, and a circuit for feedback of asignal related to the detected clearance to an electric current to beapplied to said electromagnet.

There may be a position controller for positioning said carrying member,wherein plural supporting mechanism are disposed so as not to produce amoment to said position controller.

In accordance with another aspect of the present invention, there isprovided a supporting system, comprising: a carrying member for carryingthereon a workpiece; and a supporting mechanism for supporting saidcarrying member, said supporting mechanism having a first element forproducing a resisting force to a shift in a supporting direction, and asecond element for producing a force for increasing the shift in thesupporting direction; wherein said second element can produce a forcefor moving said carrying member downwardly.

The supporting mechanism may include a spring element and a magnetelement.

Adjacent a workpiece processing position for the workpiece, a weight ofsaid carrying member and a combined force of said first and secondelements may be substantially equal to each other.

In accordance with a further aspect of the present invention, there isprovided a supporting system, comprising: a carrying member for carryinga workpiece thereon; and a supporting mechanism for supporting saidcarrying member from a workpiece transfer position to a workpieceprocessing position, said supporting mechanism having a first elementfor producing a resisting force to a shift in a supporting direction,and a second element for producing a force to increase a shift in thesupporting direction.

The second element for producing a force to increase the shift mayproduce a force to move said carrying member downwardly.

Adjacent to the workpiece processing position, the weight of saidcarrying member and a combined force of said first and second elementsmay be approximately equal to each other.

The force to be produced by said second element may be larger at thetransfer position than at the workpiece processing position.

The first and second elements may include a spring element and a magnetelement.

In accordance with a yet further aspect of the present invention, thereis provided a supporting system, comprising: a carrying member forcarrying a workpiece thereon; and a supporting mechanism for supportingsaid carrying member from a workpiece transfer position to a workpieceprocessing position, said supporting mechanism having a spring elementand a magnet element; wherein, adjacent the workpiece processingposition, the weight of said carrying member and a combined force ofsaid spring element and said magnet element are approximately equal toeach other, and wherein said magnet element has a magnet with aclearance which is smaller at the transfer position than at theworkpiece processing position.

At a certain position, the clearance of the magnet of said magnetelement may be smaller than that at the workpiece processing position,and at that position, the weight of said carrying member and thecombined force of said spring element and said magnet element may beapproximately equal to each other.

An absolute value of a changing rate of the force of said magnet elementwith respect to a change in clearance of the magnet, adjacent theworkpiece processing position, may be set smaller than an absolute valueof a changing rate of the force of said spring element with respect to achange in the clearance of the magnet.

In accordance with a still further aspect of the present invention,there is provided a supporting system, comprising: a carrying member forcarrying a workpiece thereon; and a supporting mechanism for supportingsaid carrying member from a workpiece transfer position to a workpieceprocessing position, said supporting mechanism having a spring elementand a magnet element; wherein, adjacent the workpiece processingposition, the weight of said carrying member and a combined force ofsaid spring element and said magnet element are approximately equal toeach other, and wherein said magnet element has a magnet with aclearance which is larger at the transfer position than at the workpieceprocessing position.

At a certain position, the clearance of the magnet of said magnetelement may be larger than that at the workpiece processing position,and at that position, the weight of said carrying member and thecombined force of said spring element and said magnet element may beapproximately equal to each other.

An absolute value of a changing rate of the force of said magnet elementwith respect to a change in clearance of the magnet, adjacent theworkpiece processing position, may be set larger than an absolute valueof a changing rate of the force of said spring element with respect to achange in the clearance of the magnet.

In accordance with a yet further aspect of the present invention, thereis provided a supporting system, comprising: a carrying member forcarrying a workpiece thereon; and a supporting mechanism for supportingsaid carrying member from a workpiece transfer position to a workpieceprocessing position, said supporting mechanism having a spring elementand a magnet element; wherein an absolute value of a changing rate ofthe force of said magnet element with respect to a change in clearanceof the magnet, adjacent the workpiece processing position, is setsmaller than an absolute value of a changing rate of the force of saidspring element with respect to a change in the clearance of the magnet.

In accordance with a still further aspect of the present invention,there is provided a supporting system, comprising: a carrying member forcarrying a workpiece thereon; and a supporting mechanism for supportingsaid carrying member from a workpiece transfer position to a workpieceprocessing position, said supporting mechanism having a spring elementand a magnet element; wherein an absolute value of a changing rate ofthe force of said magnet element with respect to a change in clearanceof the magnet, adjacent the workpiece processing position, is set largerthan an absolute value of a changing rate of the force of said springelement with respect to a change in the clearance of the magnet.

In accordance with a still further aspect of the present invention,there is provided a supporting system, comprising: a carrying member forcarrying a workpiece thereon; and a supporting mechanism for supportingsaid carrying member from a workpiece transfer position to a workpieceprocessing position; wherein, adjacent the transfer position, the weightof said carrying member and a force to be applied to said carryingmember are substantially balanced, and wherein, adjacent the workpieceprocessing position, the weight of said carrying member and a force tobe applied to said carrying member are substantially balanced.

The supporting mechanism may have a first element for producing aresisting force to a shift in a supporting direction, and a secondelement for producing a force for increasing the shift in the supportingdirection.

The supporting mechanism may include a spring element and a magnetelement.

In accordance with another aspect of the present invention, there isprovided an exposure apparatus, comprising: a carrying member forcarrying thereon a workpiece; and a supporting mechanism having amagnet, for supporting a weight of said carrying member; wherein a forceto be applied to said magnet does not change with a shift of saidcarrying member along a plane perpendicular to a direction in which theweight is supported.

In accordance with a further aspect of the present invention, there isprovided an exposure apparatus, comprising: a carrying member forcarrying thereon a workpiece; and a supporting mechanism for supportingsaid carrying member, said supporting mechanism having an element forproducing a force to increase/decrease a shift in a supportingdirection, wherein, as the shift in the supporting direction increases,said carrying member is moved downwardly.

In accordance with a further aspect of the present invention, there isprovided an exposure apparatus, comprising: a carrying member forcarrying a workpiece thereon; and a supporting mechanism for supportingsaid carrying member from a workpiece transfer position to a workpieceprocessing position, said supporting mechanism having a first elementfor producing a resisting force to a shift in a supporting direction,and a second element for producing a force to increase a shift in thesupporting direction.

In accordance with a still further aspect of the present invention,there is provided an exposure apparatus, comprising: a carrying memberfor carrying a workpiece thereon; and a supporting mechanism forsupporting said carrying member from a workpiece transfer position to aworkpiece processing position, said supporting mechanism having a springelement and a magnet element; wherein, adjacent the workpiece processingposition, the weight of said carrying member and a combined force ofsaid spring element and said magnet element are approximately equal toeach other, and wherein said magnet element has a magnet with aclearance which is smaller at the transfer position than at theworkpiece processing position.

In accordance with a still further aspect of the present invention,there is provided an exposure apparatus, comprising: a carrying memberfor carrying a workpiece thereon; and a supporting mechanism forsupporting said carrying member from a workpiece transfer position to aworkpiece processing position, said supporting mechanism having a springelement and a magnet element; wherein, adjacent the workpiece processingposition, the weight of said carrying member and a combined force ofsaid spring element and said magnet element are approximately equal toeach other, and wherein said magnet element has a magnet with aclearance which is larger at the transfer position than at the workpieceprocessing position.

In accordance with a yet further aspect of the present invention, thereis provided an exposure apparatus, comprising: a carrying member forcarrying a workpiece thereon; and a supporting mechanism for supportingsaid carrying member from a workpiece transfer position to a workpieceprocessing position, said supporting mechanism having a spring elementand a magnet element; wherein an absolute value of a changing rate ofthe force of said magnet element with respect to a change in clearanceof the magnet, adjacent the workpiece processing position, is setsmaller than an absolute value of a changing rate of the force of saidspring element with respect to a change in the clearance of the magnet.

In accordance with a yet further aspect of the present invention, thereis provided an exposure apparatus, comprising: a carrying member forcarrying a workpiece thereon; and a supporting mechanism for supportingsaid carrying member from a workpiece transfer position to a workpieceprocessing position, said supporting mechanism having a spring elementand a magnet element; wherein an absolute value of a changing rate ofthe force of said magnet element with respect to a change in clearanceof the magnet, adjacent the workpiece processing position, is set largerthan an absolute value of a changing rate of the force of said springelement with respect to a change in the clearance of the magnet.

In accordance with a still further aspect of the present invention,there is provided an exposure apparatus, comprising: a carrying memberfor carrying a workpiece thereon; and a supporting mechanism forsupporting said carrying member from a workpiece transfer position to aworkpiece processing position; wherein, adjacent the transfer position,the weight of said carrying member and a force to be applied to saidcarrying member are substantially balanced, and wherein, adjacent theworkpiece processing position, the weight of said carrying member and aforce to be applied to said carrying member are substantially balanced.

In accordance with an aspect of the present invention, there is provideda device manufacturing method, comprising the steps of: preparing anexposure apparatus as recited above; applying a resist to a wafer;exposing the wafer by use of the exposure apparatus; and developing theexposed wafer.

These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show a fine-motion stage of a supporting systemaccording to a first embodiment of the present invention, wherein FIG.1A is a top plan view and FIG. 1B is a front view.

FIGS. 2A and 2B show the fine-motion stage of a supporting systemaccording to the first embodiment of the present invention, wherein FIG.2A is a top plan view and FIG. 2B is a front view.

FIG. 3 is an exploded perspective view of a supporting unit in thesupporting system according to the first embodiment of the presentinvention.

FIGS. 4A and 4B show a fine-motion stage of a supporting systemaccording to a second embodiment of the present invention, wherein FIG.4A is a front view and FIG. 4B is an enlarged and exploded view of thesupporting unit thereof.

FIGS. 5A and 5B show a fine-motion stage of a supporting systemaccording to a third embodiment of the present invention, wherein FIG.5A is a front view and FIG. 5B is an enlarged and exploded view of thesupporting unit thereof.

FIGS. 6A and 6B show a fine-motion stage of a supporting systemaccording to a fourth embodiment of the present invention, wherein FIG.6A is a top plan view and FIG. 6B is a front view.

FIGS. 7A and 7B show a fine-motion stage of a supporting systemaccording to the fourth embodiment of the present invention, with aportion being demounted, wherein FIG. 7A is a top plan view and FIG. 7Bis a front view.

FIGS. 8A and 8B show a first modified example of the fourth embodiment,wherein FIG. 8A is a top plan view and FIG. 8B is a front view.

FIG. 9 is an enlarged perspective view of a portion of FIG. 8.

FIG. 10 is an enlarged perspective view, showing a second modifiedexample of the fourth embodiment of the present invention.

FIGS. 11A and 11B show a fine-motion stage of a supporting systemaccording to a fifth embodiment of the present invention, wherein FIG.11A is a front view and FIG. 11B is an enlarged and exploded view of thesupporting unit thereof.

FIGS. 12A and 12B show a modified example of the fifth embodiment of thepresent invention, wherein FIG. 12A is a front view and FIG. 12B is anenlarged and exploded view of the supporting unit thereof.

FIGS. 13A, 13B and 13C show a fine-motion stage of a supporting systemaccording to a sixth embodiment of the present invention, wherein FIG.13A is a top view, and FIGS. 13B and 13C are front views.

FIG. 14 is an enlarged view of a portion of FIGS. 13A-13C.

FIG. 15 is a front view, showing a first modified example of the sixthembodiment of the present invention.

FIG. 16 is a front view, showing a second modified example of the sixthembodiment of the present invention.

FIG. 17 is a front view, showing a third modified example of the sixthembodiment of the present invention.

FIG. 18 is a front view, showing a fourth modified example of the sixthembodiment of the present invention.

FIGS. 19A, 19B and 19C show a fine-motion stage of a supporting systemaccording to a seventh embodiment of the present invention, whereinFIGS. 19A and 19B are front views and FIG. 19C is an enlarged andexploded view.

FIG. 20 is a front view, showing a first modified example of the seventhembodiment of the present invention.

FIG. 21 is a front view, showing a second modified example of theseventh embodiment of the present invention.

FIG. 22 is a front view, showing a third modified example of the seventhembodiment of the present invention.

FIG. 23 is a front view, showing a fourth modified example of theseventh embodiment of the present invention.

FIGS. 24A, 24B, 25, 26 and 27 are graphs each showing an example ofbalancing condition for a magnet and a spring, in a supporting systemaccording to the present invention.

FIG. 28 is a perspective view of a conventional supporting system.

FIGS. 29A and 29B show a fine-motion stage of a conventional supportingsystem, wherein FIG. 29A is a top plan view and FIG. 29B is a frontview.

FIGS. 30A and 30B show a fine-motion stage of a conventional supportingsystem, wherein FIG. 30A is a plan view and FIG. 30B is a front view.

FIG. 31 is a flow chart for explaining an embodiment of a devicemanufacturing method using an exposure apparatus having a supportingsystem of the present invention.

FIG. 32 is a flow chart for explaining details of the wafer process inthe procedure of FIG. 31.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be describedwith reference to the accompanying drawings.

Now, embodiments of the present invention will be described particularlyin relation to a supporting system used in an exposure apparatus whereina wafer is taken as a workpiece.

First Embodiment

FIGS. 1A, 1B, 2A and 2B show a fine-motion stage of a supporting systemaccording to a first embodiment of the present invention, wherein FIG.1A is a top plan view, FIG. 1B is a front view wherein a yoke of a Zlinear motor is demounted, FIG. 2A is a top plan view wherein a waferstage top plate is demounted, and FIG. 2B is a front view wherein a Zsuspension driving unit 2-1 is demounted. The fine-motion stage 1 of thesupporting system is mounted on an X stage top plate 11 and it functionsto position a wafer W (workpiece) with respect to six axial directionsof X, Y, Z, tilt and θ. By means of four Z suspension driving units 2-1to 2-4 provided at the peripheral portion, a wafer stage top plate 12(carrying member) is supported and positioned with respect to Z tiltdirection. Also, by means of an X-Y-θ driving unit 3 provided at thecentral portion, the wafer stage top plate 12 is positioned with respectto the X, Y and θ directions. The wafer stage top plate 12 carriesthereon a wafer which is to be positioned.

The Z suspension driving unit 2 (2-1 to 2-4) includes a Z linear motor 4and a weight supporting mechanism 5. The Z linear motor functions toapply a force in Z direction to the wafer stage top plate 12. The weightsupporting mechanism 5 operates to support the weight of the wafer stagetop plate 12, and functions at least to intercept transmission ofvibration in a direction along a plane of a pattern.

The Z linear motor 4 comprises a flat coil 16 having a major orlengthwise side parallel to a horizontal line, four magnets 17 opposed,through a gap, to the major side of the flat coil 16, and two yokes 18for circulating the magnetic flux of the magnets 17. The flat coil 16 isfixed to the X stage top plate 11, and the magnets 17 and the yokes 18are fixed as a unit to the wafer stage top plate 12. As an electriccurrent is applied to the flat coil 16, a force in the Z directionoperates between the coil 16 and the integral structure of the magnet 17and the yoke 18.

The weight supporting mechanism 5 comprises an attraction magnet 23, alifting iron plate 27 to be attracted by the magnet 23, iron platesupporting members 28 for supporting opposite ends of the iron plate 27(details are shown in FIG. 3). The magnet 23 comprises a column-likemagnet element 24 being magnetized vertically, and a yoke 25 forcirculating the magnetic flux of the magnet element 24. The yoke 25 is amagnetic member such as iron, for example, having a ring-like protrusion25 b formed on its flat portion 25 a. The magnet element 24 is fixed atthe central portion of the ring-like protrusion 25 b of the yoke 25.Here, the weight to be supported by the weight supporting mechanism 5includes the weights of the magnet 17, yoke 18 and magnet 23, movable asa unit with the wafer stage top plate 12. This applies to otherembodiments to be described later.

As regards the coupling relation, the opposite ends of the flat plate 25a of the yoke 25 are fixed to the linear motor yoke 18, and the ironplate 27 are fixed to the flat coil 16 of the Z linear motor 4 throughthe two iron plate supporting members 28. As a result, the magnetelement 24 of the attracting magnet 23 and the iron plate 27 aredisposed opposed to each other with a small clearance kept therebetween,such that an attraction force operates between them. The iron plate 27is fixed to the X stage top plate 11 through the supporting members 28and the flat coil 16 of the Z linear motor 4, and the attracting magnet23 is fixed to the wafer stage top plate 12 through the linear motorcoil 18. Thus, with an attraction force acting between the magnet 23 andthe iron plate 27, the wafer stage top plate 12 receives an attractionfloating force from the X stage top plate 11. In order that anattraction floating force operates from the X stage top plate 11,disposed below, to the wafer stage top plate 12 disposed above, as shownin FIG. 3, a telescopic structure wherein the magnet element 24 isplaced inside is used.

The size along a plane perpendicular to the attracting direction of theiron plate 27 is made larger by at least a few centimeters than that ofthe ring-like protrusion 25 b of the attracting magnet 23.Alternatively, it is made sufficiently large as compared with the gap orclearance between the magnet 23 and the iron plate 27. With thisarrangement, even if the attracting magnet 23 and the iron plate 27shift along a plane perpendicular to the attracting direction, theresisting force (resilience force) there of in the shift direction canbe made substantially zero. This is because the size along a planeperpendicular to the attracting direction of the iron plate 27 is madeslightly larger, a shift in that direction causes substantially nochange in the boundary condition of the magnetic lines of force producedbetween the attracting magnet 23 and the iron plate 27, such that thereoccurs substantially no change in the distribution of magnetic lines offorce. Thus, the supporting portion can be free along that plane.

The Z linear motor 4 does not bear the function of weight support but itoperates solely for the position control. Thus, an electric currentwhich may otherwise cause a problem of heat generation is not flownthereto. This is as like the conventional structure described above.

As shown in FIGS. 1A, 2A and 2B, the X-Y-θ driving unit 3 comprises across-shaped stator 31 and a cross-shaped movable element 36. The stator31 has X coils 33 a and 33 b and Y coils 34 a and 34 b which areinserted into a cross-shaped frame 32. It is fixed to the X stage topplate 11 through a frame supporting member 35. The movable element 36has a cross-shaped upper yoke 37, a cross-shaped lower yoke 38, forL-shaped side plates 39, and four (upper two and lower two) magnets 40.Upon the upper and lower yokes 37 and 38, the magnets 40 are disposed atpositions to be opposed to the corresponding coils 33 a, 33 b, 34 a and34 b of the stator 31. By using the side plates 39 as a spacer, theupper and lower yokes 37 and 38 are combined to vertically sandwich thestator 31 therebetween, and the resultant integral structure is fixed tothe wafer stage top plate 12. The lengthwise side of each X coils 33 aand 33 b is disposed at a right angle to the X direction, while thelengthwise side of each Y coils 34 a and 34 b is disposed at a rightangle with the Y direction. As an electric current is flown to the Xcoils 33 a and 33 b, a force in X direction is produced between thestator 31 and the movable element 36. Also, as an electric current isapplied to the Y coils 34 a and 34 b, a force in the Y direction isproduced between the stator 31 and the movable element 36. Further, amoment in θ direction can be produced by superposing couple componentsby means of the X and Y coils 33 a-34 b.

In this embodiment, the Z linear motor may be conventional. Although useof three motors is enough, there are four motors used. This is toprovide symmetry in the whole geometrical shape and to assuregeometrical symmetry in the linear motor disposition, thereby to make iteasy to push the gravity center by fine-motion linear motors. Further,since two linear motors 4 are disposed along the X driving axis whileother two are disposed along Y driving axis, independent control of themoment about the X axis and the moment about the Y axis is easy.However, use of three-motor driving system as conventional may beadopted, with an effect of interception of vibration along a planeperpendicular to the supporting direction, although the advantagesdescribed above are not obtainable.

As regards the X-Y-θ driving system, while use of three motors isenough, there are four motors used, particularly for the geometricalsymmetry. In the X-Y-θ driving system, the easiness of pushing thegravity center or independent controllability for respective axes aresubstantially unchanged by use of the three-motor system, as like theexample to be described with reference to FIG. 8. Therefore, a threelinear motor structure may be used in the X-Y-θ driving unit, such asshown in FIG. 8.

With the structure described above, a wafer W can be positionedprecisely with respect to X, Y, Z, θ and tilt directions, by applyingappropriate electric currents to coils of the rough-motion X,rough-motion Y, fine-motion X1, fine-motion X2, fine-motion Y1,fine-motion Y2, fine-motion Z1, fine-motion Z2, fine-motion Z3, andfine-motion Z4, through a control system (not shown). Then, an exposureprocess is performed by using exposure means (not shown), a pattern ofan original (not shown) is sequentially printed on the wafer W. Here,any vibration disturbance to be transmitted to a plane perpendicular tothe weight supporting direction, is blocked by the freedom of theattracting magnet 23 along that plane, such that the position controlprecision is improved significantly.

Second Embodiment

FIGS. 4A and 4B show a fine-motion stage of a supporting systemaccording to a second embodiment of the present invention, wherein FIG.4A is a front view in a state in which a yoke in front of a Z linearmotor is demounted, and FIG. 4B is an enlarged perspective view of thatportion. In the fine-motion stage 1 of this supporting system, thelifting iron plate 27 of the first embodiment is replaced by an uppermagnet unit 41 having an upper yoke 42 and upper magnets 43 a and 43 b.Also, the attracting magnet 23 of the first embodiment is replaced by alower magnet unit 46 which comprises lower magnets 47 a and 47 b as wellas a lower yoke 48. The upper magnets 43 a and 43 b and the lowermagnets 47 a and 47 b are magnetized so that they attract each other. Inthe first embodiment, the combination of the ion plate 27 and the magnet23 is used to assure the attracting function as well as the freedom(release) along the plane perpendicular to the attracting direction. Inthis embodiment, similar functions are provided by placing, opposed toeach other, the upper and lower magnets 43 and 47 of rectangular shapeand having different sizes. Even with magnets solely, if there is adifference maintained between them in respect to the size along a planeperpendicular to the attracting direction, it is possible to assure thata shift along the plane perpendicular to the attracting direction doesnot cause a substantial change in the distribution of magnetic lines offorce. Therefore, like the first embodiment, any vibration along a planeperpendicular to the attracting direction can be intercepted.

In the fine-motion stage 1 of this embodiment, the lower magnet unit 46is fixed to the wafer stage top plate 12 disposed above, while the uppermagnet unit 41 is fixed to the X stage top plate 11 disposed below. Withthe support through a telescopic structure including the upper magnetsupport, a floating force is applied from the lower X stage top plate 11to the upper wafer stage top plate 12. This is the same as the firstembodiment. The six-axis fine-motion mechanism itself is of the samestructure as has been described with reference to the first embodiment.

Third Embodiment

FIGS. 5A and 5B show a fine-motion stage of a supporting systemaccording to a third embodiment of the present invention, wherein FIG.5A is a front view in a state in which a yoke in front of a Z linearmotor is demounted, and FIG. 5B is an enlarged perspective view of thatportion. In the fine-motion stage 1 of this embodiment, the magnetstructure is similar to that of the second embodiment, and it comprisesan upper magnet unit 41 having an upper yoke 42 and upper magnets 43 aand 43 b, as well as a lower magnet unit 46 having lower magnets 47 aand 47 b and a lower yoke 48. There is a difference held between them,in respect to the size along a plane perpendicular to the floating forceproducing direction. This embodiment differs from the second embodimentin that the upper magnets 43 a and 43 b and the lower magnets 47 a and47 b are magnetized so as to produce a mutually repulsion force, andthus a repulsive magnet unit 49 is provided. The coupling relation ofthese magnets is inverse to that of the second embodiment. The lowermagnet unit 46 is fixed to a flat coil 16 of the Z linear motor 4through the lower yoke 48, while the upper magnet unit 41 is fixed tothe wafer stage top plate 12 through the upper yoke 42. Since arepulsion force operates to them, a telescopic structure as used in thesecond embodiment is not necessary. By simply fixing the magnets to thetop plates 12 and 11, respectively, a floating force can be applied fromthe X stage top plate 11 to the wafer stage top plate 12. Thus, thestructure is simple as compared with the second embodiment. Even withuse of repulsive magnets, if a difference is created in the size along aplane perpendicular to the repulsion direction, a mutual shift betweenthem along that plane does not cause a substantial change in thedistribution of magnetic lines of force. Thus, like the firstembodiment, any vibration along a plane perpendicular to the floatingdirection can be intercepted. The six-axis fine-motion mechanism itselfis the same as in the first embodiment.

Fourth Embodiment

FIGS. 6A, 6B, 7A and 7B show a fine-motion stage of a supporting systemaccording to a fourth embodiment of the present invention, wherein FIG.6A is a top view, FIG. 6B is a front view in a state in which a yoke infront of a Z linear motor is demounted, FIG. 7A is a top view in which awafer stage top plate is demounted, and FIG. 7B is a front view in whicha front Z suspension driving unit is demounted.

The fine-motion stage 1 of this embodiment is mounted on an X stage topplate 11 and it functions to position a wafer W (workpiece) with respectto Z tilt θ direction. While guides and driving systems thereof areconventional, there are Z suspension driving units 2 (2-1 to 2-3) asused in the first embodiment of FIGS. 1-3, disposed at three locationsand, additionally, there is a universal joint 6 at the center. Thisdiffers from the first embodiment. The universal joint 6 comprises anouter circular ring 51 fixed to the top face of the X stage top plate11, and an inner circular ring 52 disposed inside the outer ring 51 andfixed to the bottom face of the wafer stage top plate 12. There is anair between the outer and inner rings 51 and 52, and the universal joint6 functions to relatively guide the X stage top plate 11 and the waferstage top plate 12, while confining relative shift in X and Ydirections, to enable rotation, Z axis motion and Z tilt.

The Z linear motors 4 of the Z suspension driving unit 2 (2-1 to 2-3) aswell as the weight supporting mechanism 5 are of the same structure asof the first embodiment. Duplicate description is omitted, by assigningthe same reference numerals to corresponding components. The Z linearmotor 4 does not bear the function of weight support but it operatessolely for the position control. Thus, an electric current which mayotherwise cause a problem of heat generation is not flown thereto. Thisis the same as the first embodiment.

With the structure described above, a wafer W can be positionedprecisely with respect to X, Y, Z, θ and tilt directions, by applyingappropriate electric currents to coils of the rough-motion X,rough-motion Y, fine-motion X1, fine-motion X2, fine-motion Y1,fine-motion Y2, fine-motion Z1, fine-motion Z2, fine-motion Z3, andfine-motion θ, through a control system (not shown). Then, an exposureprocess is performed by using exposure means (not shown), a pattern ofan original (not shown) is sequentially printed on the wafer W.

Here, any vibration disturbance to be transmitted to a planeperpendicular to the weight supporting direction, is blocked by thefreedom of the attracting magnet 23 along that plane, such that theposition control precision is improved significantly. Further, sincethis embodiment does not use an air or rubber film, the reliability isimproved.

FIGS. 8A, 8B and 9 show a first modified example the attraction magnetunit in the fourth embodiment of the present invention, wherein FIG. 8Ais a top plan view, FIG. 8B is a front view and FIG. 9 is a perspectiveview. In the fourth embodiment shown in FIGS. 6 and 7, the system is sostructured that a shift of the magnet and the iron plate in anydirection does not apply a substantial resisting force (resilienceforce) in the shift direction. In this modified example, however, theshift direction in which the resisting force does not apply isrestricted to one direction. In the example of FIG. 3, the column-likemagnet element 24 is fixed to the yoke 25 having a ring-like protrusion25 b, and this yoke 25 is fixed to the linear motor yoke 18 which isintegral with the wafer stage top plate 12. In this modified example, ascompared therewith, two rectangular parallelepiped magnets 55 are fixedto a flat plate-like yoke 48, and this yoke 48 is fixed to a linearmotor yoke 18 which is integral with the wafer stage top plate 12. Thetwo magnets 55 are vertically magnetized, respectively, and one ismounted so its N pole faces up and the other is mounted so that its Spole faces up. A floating force is applied to the magnets 55 from theiron plate 27 to float the wafer stage top plate 12, this being the sameas in the example of FIG. 3.

A largest difference of this embodiment over the FIG. 3 example is thatthe sizes of the iron plate 27 and the two magnets 55 as a whole, alongthe plane perpendicular to the floating force direction, are differentonly in one direction. In the FIG. 3 example, the size of the iron plate27 in the direction perpendicular to the floating force is generallylarger than the diameter of the ring-like protrusion 25 b of the yoke25, so that, even if the magnet 23 shifts in any direction relative tothe iron plate 27, a resisting force does not substantially apply. Inthe present modified example, as compared therewith, as regards the sizein the direction perpendicular to the floating force of the iron plate27, it is larger than the two magnets 55 as a whole in respect to thedirection along the lengthwise direction of the flat coil 16, whereas itis approximately the same as the size of the two magnets 55 in respectto a direction normal to the lengthwise direction. As a result of this,if the magnet 55 shifts relative to the iron plate 27 in the directionalong the lengthwise direction of the flat coil 16, substantially noresilience force operates. However, if the shift is in any otherdirection, a large resilience force is applied.

The Z suspension driving unit 2 (2-1 to 2-3) comprising the Z linearmotors 4 and the weight supporting mechanism 5, is disposed along thecircumferential direction of the universal joint 6, as shown in FIG. 8.

With this arrangement, due to the confining action of the universaljoint 6, the magnets 55 and the iron plate 27 move only in thecircumferential direction of the universal joint 6. Namely, they shiftonly in the direction in which a resilience force does not operate inresponse to the shift. In other words, even if a resilience forceoperates as the shift occurs in any other direction, practically, thereoccurs no shift in such direction.

When the margin for the size of the iron plate 27 with respect to themagnet 55 is limited only to one direction, it saves the space for anyother direction. Therefore, the mass or space can be savedadvantageously.

FIG. 10 show a second modified example of the attracting magnet unit inthe fourth embodiment of the present invention. While the basicstructure is the same as the first modified example shown in FIGS. 8 and9, in this example the size of the magnet 55 in the direction along thelengthwise direction of the flat coil 16 are further enlarged, and thesize in the direction perpendicular to that direction is made shorter.Since the floating force is proportional to the area with which themagnet 55 and the iron plate 27 are opposed to each other, once the areais kept constant, the floating force can be maintained even though theaspect ratio of the parallelepiped is changed.

In the example shown in FIG. 10, the Z suspension driving unit 2 isdisposed so that the direction in which the resilience force does notsubstantially operate is put along the circumferential direction of theuniversal joint 6, such that, due to the confinement by the joint 6, theshift can occur only in the direction in which substantially noresilience force operates. The difference over the first modified formof FIG. 9 is that, as compared with the first modified example, in thesecond modified example the resilience force against the shift in thedirection along the lengthwise side of the flat coil 16 is furthersmaller, and that a large resilience force applies, to the contrary, inresponse to a shift in the direction perpendicular to the lengthwisedirection. This is because the width of the region in which the magneticfield changes in response to a shift along the lengthwise direction ofthe flat coil 16 is proportional to the magnet size in the directionperpendicular to the coil lengthwise direction. As compared with thefirst modified example of FIG. 9, in the second modified example themagnet size in the direction perpendicular to the length of the flatcoil 16 is smaller. Therefore, in response to a shift in the lengthwisedirection of the flat coil 16, the region of magnetic field change isnarrower in this example than in the first modified example, such thatthe energy change is smaller.

Even if the size ratio of the magnet 55 is changed, similarly, due tothe confinement of the universal joint 26, the magnet 55 and the ironplate 27 can shift only in the θ direction of the wafer top plate 12.Since the resilience force responsive to the shift in that directionbecomes further smaller, the vibration interception performance of thewafer stage top plate 12 in the θ direction is improved. Alternatively,this characteristic may be used to reduce the margin of size of the ironplate 27, without using the same for the performance increase. Althoughthe resilience force becomes larger as the margin size of the iron plateto the magnet 55 in the shift direction becomes smaller, since theresilience force can be reduced if the magnet size in the directionperpendicular to the shift direction is set small. Thus, in total,without increase of the resilience force, namely, without degrading thevibration interception performance, the margin of size of the iron plate27 with respect to the magnet can be reduced.

In the first and second modified examples of FIGS. 9 and 10, the N and Spoles are disposed along the widthwise direction of the magnet 55. As aresult, as the absolute value of the short size becomes smaller, thedepth of penetration of the magnetic flux of the magnet 55 into the yoke48 below and the iron plate 27 above becomes shallower. Thus, thesmaller the absolute value of the short size is, the thinner thethickness of the yoke 48 below and the iron plate 27 above can be. Thetotal height can therefore be reduced. This is an advantageous result,obtained by restricting the freedom of resilience force along a planeinto the freedom only in a single direction.

In summary, in the first and second modified examples of FIGS. 9 and 10,a particular one direction is distinguished over the other directionsand the freedom in the particular direction is enhanced, by which thefreedom in that direction, namely, the vibration interceptingcharacteristic, can be improved. Also, without degrading the vibrationisolating property, the margin in size of the iron plate 27 relative tothe magnet 55 can be reduced, and the total height can be made smaller.

In the fourth embodiment, like the example shown in FIG. 1, four Zsuspension driving units 2 may be used. In the example of FIG. 8, thereare three Z suspension driving units 2 (2-1 to 2-3) disposed along thecircumferential direction. However, in this example, four units may beused and disposed so that the direction in which substantially noresilience force operates is put along the circumferential direction ofthe universal joint 6. The freedom to be controlled concerns Z directionand tilt, and use of three driving units is enough. However, four unitsmay be used. In that occasion, geometrical symmetry is assured withrespect to both the X and Y directions and, therefore, the gravitycenter and the action point can easily be registered with each other.Further, in the tilt driving, the influence of any other component canbe minimized.

What is important in this structure is that the direction in which noresilience force acts is registered with the circumferential directionof the universal joint 6. Any other component such as, for example, thelengthwise direction of the flat coil 16, is not important. Namely,while in the fourth embodiment the lengthwise direction of the magnet 55is put in the same direction as the lengthwise side of the flat coil 16,they may be different from each other. However, where the aspect ratioof the size of the magnet 55 largely differs as shown in FIG. 10,registering the lengthwise directions of the magnet and the coil will beadvantageous in respect to the space saving.

Fifth Embodiment

FIGS. 11A and 11B show an attraction magnet unit in a fifth embodimentof the present invention, wherein FIG. 11A is a front view in a state inwhich a yoke in front of a Z linear motor is demounted, and FIG. 11B isan enlarged perspective view of that portion. In the fourth embodimentand the first and second modified forms thereof, the combination of aniron plate and a magnet is used to assure the attracting function aswell as the freedom (release) along the plane perpendicular to theattracting direction. In this embodiment, similar functions are providedby use of a combination of an iron plate and an electromagnet. Theelectromagnet can produce a large attracting force with a very smallampere turn, as contrasted to the linear motor and, therefore, acondition without a large heat generation can be set in such use as theweight support wherein continuous energization is required. Thus, it canbe used in place of a permanent magnet.

The attraction magnet unit in this embodiment comprises an electromagnet61 having a coil 63 wound around the central portion of a laminated yoke62 having an approximately E-shaped section, and a laminated liftingiron plate 67 having an approximately I-shaped section and beingdisposed opposed to the electromagnet 61. In response to an electriccurrent flown to the coil 63 at the center of the yoke 62, an attractionforce is produced between them. The electromagnet 61 disposed below isfixed to the wafer stage top plate 12 disposed above, through anelectromagnet holder 64 and the yoke 18. The iron plate 67 disposedabove is fixed to the flat coil 16 through an iron plate supportingmember 28.

At the plane as opposed, the size of the iron plate 67 in the planeperpendicular to the attracting direction and specifically along thelengthwise direction of the flat coil 16, is made larger than theelectromagnet 61. The size in the direction perpendicular to thatdirection is approximately the same as the electromagnet 61.

Thus, when an electric current is flown through the coil 63 at thecenter of the yoke 62 to produce an attraction force between theelectromagnet 61 and the iron plate 67, the distribution of the magneticlines of force does not substantially change even if a shift occurs in adirection along the length of the flat coil 16 under similar conditionsas those of the first and second modified examples of the fourthembodiment. As a result, vibration in the direction along the length ofthe coil 16 can be blocked, as in the first and second examples of thefourth embodiment. On the other hand, any vibration in a directionperpendicular to that direction is relatively transmitted. The Zsuspension driving unit 2 is disposed so that the direction in which thevibration is blocked is placed along the circumferential direction ofthe universal joint 6, as shown in FIGS. 8, 9 and 10. As a result, likethe fourth embodiment and the first and second modifications thereof,vibration in θ direction to the wafer stage top plate 12 can beintercepted.

Further, as regards the electromagnet 61, as in the examples of FIGS. 8,9 and 10, the vibration blocking performance is improved with a largerdifference in longitudinal and lateral sizes of the surface opposed tothe iron plate 67. Also, the margin of size can be saved withoutdegrading the vibration blocking performance.

The magnetic poles as formed by the electromagnet 61 of FIG. 11 aredisposed along a widthwise (minor) direction of the opposed area withthe iron plate 67. For example, if there is an N pole at the center ofthe yoke 62, there are S poles at the opposite ends. If there is an Spole at the center, there are N poles at the opposite ends. Therefore,in the same condition as described in relation to FIG. 9 or 10, with asmaller absolute value of the short (width) size, the depth ofpenetration of the magnetic flux into the lower portion of the yoke 62or iron plate 67 can be made smaller. This enables reduction inthickness of the ion plate 67 and yoke 62, and also reduction in totalheight.

Also in the case of the electromagnet 61, by confining the freedom in aparticular one direction, the vibration intercepting characteristic canbe improved. Also, without degrading the vibration isolating property,the margin in size of the iron plate 67 relative to the electromagnet 61can be reduced, and the total height can be made smaller.

As a matter of course, the electromagnet 61 may be used without anylimitation to the vibration blocking direction, as in the example ofFIG. 3.

There is an advantage peculiar to the electromagnet 61. By adjusting theelectric current, the floating force of the wafer stage top plate 12 canbe adjusted. If a permanent magnet is used, the adjustment of thefloating force or repulsion force needs adjustment of changing the gap,and this need a specific mechanism. In the case of the electromagnet 61,on the other hand, only changing the electric current is necessary. Thiscan be done without mechanical adjustment, and it can be done through aremote control.

In the example shown in FIG. 11, the E-shaped yoke 62 of theelectromagnet 61 and the I-shaped iron plate 67 each comprises alaminated (layered) structure of thin plates. This structure is adoptedto assure that the electromagnet 61 performs the function of a Z linearmotor 4, namely, the positioning function, based on the controllabilityof the force of the electromagnet 61.

Where only the weight should be supported, the change in electriccurrent through the coil is small and, therefore, the E-shaped yoke orthe I-shaped member may of course be made of a solid material. However,for precise position control, a current frequency of 100 Hz or more isrequired and, therefore, an eddy current may be created in the yoke tocause a phase delay or a force to the current phase. When the servo gainis raised, oscillation will occur in the system due to the phase delayof the force. Where the yoke 62 and the iron plate 67 have a laminated(layered) structure made from thin plates, the eddy current can be madevery small. Therefore, the phase delay of force to the electric currentcan be at a level of 1 KHz or higher, causing substantially no problem.In that case, the electromagnet 61 provides a position control function.In FIG. 11, the position control is performed by linear motors, and thusthere are Z linear motors disposed in parallel. However, these linearmotors may be omitted, and only the electromagnet may be used. In thatoccasion, the electromagnet 61 may be directly fixed to the X stage topplate 11, and supported thereby.

Using the electromagnet 61 for weight support may involve aninconvenience that, since a change in force with a gap is large,vibration in the supporting direction is easily transmitted. In order toprevent it, a gap sensor (not shown) may be used such that the gapchange is fed back to the electric current to the electromagnet 61, tothereby intercept the vibration due to the gap change.

Also in this embodiment, in place of using an attraction force of amagnet and a magnetic material, an attraction force may be produced byusing magnets.

In place of producing a floating force by use of a magnetic attractionforce, a repulsion force may be produced by use of a magnet force. Inthat occasion, the support structure does not need a telescopicstructure (FIGS. 3, 8, 10, 11), and the whole height can be made small.

FIGS. 12A and 12B show a modified example of the fifth embodiment of thepresent invention, wherein FIG. 12A is a front view in a state in whicha yoke in front of a Z linear motor is demounted, and FIG. 12GB is anexploded perspective view. In this supporting system, an electromagnet61 is fixed to the flat coil 16 side, and a laminated iron plate 67 isfixed to the wafer stage top plate 12 side.

At the opposed portion between the electromagnet 61 and the iron plate67, the size of the iron plate along a plane perpendicular to theattracting direction is made larger than that of the electromagnet 61.As a result, when an electric current is flown to the coil 63 at thecentral portion of the yoke 62 to produce an attraction force betweenthe electromagnet 61 and the iron plate 67, a mutual shift in adirection along the plane perpendicular to the attracting direction doesnot cause a substantial change in the distribution of magnetic lines offorce. Thus, any vibration along the plane perpendicular to theattracting direction can be intercepted.

The iron plate 67 disposed below is fixed to the wafer stage top plate12 disposed above, through the yoke 18. The electromagnet 61 disposedabove is fixed to the flat coil 16 through an electromagnet holder 64and an supporting member 28. The attraction element disposed below isfixed to the wafer stage top plate 12 side disposed above, while theattraction element disposed above is fixed to the X stage top plate 11disposed below. Namely, the support is made in a telescopic structure.With this arrangement, the floating force is applied from the X stagetop plate 11 disposed below to the wafer stage top plate 12 disposedabove, such that substantially the same advantageous results as those ofthe fifth embodiment (FIG. 11) are attainable.

Sixth Embodiment

FIGS. 13A, 13B and 13C show a fine-motion stage of a supporting systemaccording to a sixth embodiment of the present invention, wherein FIG.13A is a top view, and FIGS. 13B and 13C are front views in a state inwhich a yoke in front of a Z linear motor is demounted.

In this embodiment, in order to place a wafer W on the fine-motion stage1, a transfer mechanism for transferring the wafer W from a hand to thefine-motion stage 1 is necessary. A portion of this mechanism isprovided by the fine-motion stage 1. In the supporting system of thisembodiment, in addition to the structure of the first embodiment, thatis, the weight supporting system based on the attraction magnet 23 oftelescopic structure wherein a difference in size is set along a planeperpendicular to the attracting direction, there is a leaf spring 71with an evasion 74 provided in parallel. Further, in consideration ofthe transfer operation, there is a recess 88 which is formed at the topof the weight supporting system based on the attraction magnet 23 oftelescopic structure.

The leaf spring 71 in this embodiment produces a force for supportingthe weight, and the plate surfaces thereof faces up and down. Since itis rigid in a plane perpendicular to the flexure direction, it can notintercept vibration along the plane perpendicular to the supportingdirection. In consideration of it, as shown in FIG. 14, the evasions 74are provided in series to the leaf spring 71, so as to prevent that,when the X stage top plate 11 and the wafer stage top plate 12 shiftalong the plane perpendicular to the supporting direction, a resilienceforce is applied in the shift direction.

An end of the leaf spring 71 is fixed to the upper side of the flat coil16, fixed to the X stage top plate 11, through a leaf spring supportingmember 72. A lower channel-shaped member 75 is fixed to the other end ofthe leaf spring 71. The outside face of the member 75 and two opposedfaces of a window-shaped leaf spring 76 are fixed to each other. Theupper side of a channel-shaped member 77 is fixed to the wafer stage topplate 12. The leaf spring 76 is rigid with respect to the verticaldirection and it is flexible in the horizontal direction. Therefore,when a shift occurs along a plane perpendicular to the supportingdirection, it functions well to minimize the resilience (resisting)force in the shift direction. This embodiment uses two sets of suchcomponents, each set comprising an upper channel-shaped member 77, awindow-shaped leaf spring 76, a lower channel-shaped member 75, a leafspring 71 and a leaf spring supporting member 72. These two sets aredisposed at the upper side of the flat coils 16, at geometricallysymmetric positions. Where only one set of leaf spring support is used,there may occur a moment in addition to the supporting force. By usingtwo sets geometrically symmetrically, production of moment is prevented.Any number of sets may be used, provided that geometrical symmetry isassured. The structure of the six-axis fine-motion mechanism itself isthe same as the first embodiment. Any vibration disturbance along aplane perpendicular to the supporting direction can be reduced, and thepositional precision can be improved.

The attracting magnet 23 of telescopic structure having a sizedifference along a plane perpendicular to the attracting direction andthe leaf spring 71 with an evasion 74 provide the weight supportingfunction and the vibration intercepting function, as has been describedwith reference to the embodiments. Also in this embodiment, they produceadvantageous results similar to those of the first to fifth embodiments.

Here, duplicate use of the attraction magnet 23 and the leaf spring 71with an evasion 74, having similar functions, will now be explained indetail. In the attracting magnet 23 of telescopic structure having adifference in size along a plane perpendicular to the attractingdirection, in response to a shift of the iron plate in the attractingdirection, a force opposite to the resilience force is produced. Namely,it has a negative rigidity. On the other hand, with the leaf spring 71,a resilience force operates against the displacement of the leaf spring71. Namely, it has a positive rigidity. Combining an element having anegative rigidity and an element having a positive rigidity provides animportant meaning, in the fine-motion stage which provides a portion ofthe function as the transfer mechanism, as follows.

In this embodiment, the portion of the transfer function which thefine-motion stage 1 bears is the retracting function. FIG. 13B shows astate in which the wafer stage top plate 12 is not retracted. FIG. 13Cshows a state in which the top plate 12 is retracted downwardly.

It is now assumed that the fine-motion stage 1 having no wafer W carriedthereon is in the state of FIG. 13B. Subsequently, a wafer hand (notshown) takes a wafer W to the above of the fine-motion stage 1. Then,the wafer stage top plate 12 of the fine-motion stage 1 is retracteddownwardly (FIG. 13C). At this time, there remains a portion notretracted, and it is the protrusion 87 shown in FIG. 13C. Since there isa recess 88 formed in the top plate 12, the iron plate 27 and the topplate 12 do not contact with each other. In an case where the weight issupported by a telescopic structure and where the subject to besupported is retracted, it is necessary to provide similar retractionspaces 89 a and 89 b at upper and lower sides of the telescopicstructure. Subsequently, the wafer hand returns while leaving the waferW there. Then, the wafer stage top plate 12 moves again upwardly to itsoriginal position to hold the wafer W. After this, the stage moves to apredetermined position, and an exposure process is performed.

In this procedure, the operation for retracting and moving up again thewafer stage top plate 12 is accomplished by applying an electric currentto the flat coil 16 to produce a force in the Z direction. Theretraction stroke is a few millimeters. If the weight should besupported only by the attracting magnet 23 or only by the leaf spring71, the linear motor 4 should produce a force corresponding to thechange in supporting force of the supporting mechanisms in response tothe shift in Z direction, and heat generation resulting from it can notbe disregarded. Due to the heat generation, thermal deformation of thestage top plate 12 may occur.

Where the attraction magnet 23 with negative rigidity and the leafspring 71 with positive rigidity are used in combination, when the waferstage top plate 12 retracts by a few millimeters, from the state of FIG.13B to the state of FIG. 13C, the gap is expanded and the attractingforce of the magnet 23, that is, the floating force, is reduced. On theother hand, at the leaf sprint 71, the flexure increases to enlarge thespring force and thus the floating force. Thus, through appropriatesetting, changes in force of them can be substantially cancelled.

As a result of this, even when the top plate 12 is retracted by a fewmillimeters for wafer placement, heat generation at the linear motor 4can be suppressed and, thus, thermal deformation of the top plate 12 canbe prevented. Further, in respect to the vibration transmission in thesupporting direction, cancellation of the spring constants is effectiveto improve the vibration blocking performance in the supportingdirection.

FIGS. 15 and 16 show modified examples of the sixth embodiment of thepresent invention. FIG. 15 shows an example wherein, in place of theleaf spring 71 with evasion 74, the element having a positive rigidityis provided by a plurality of coil springs 91 which are disposed betweenthe top face of the X stage top plate 11 and the bottom face of thewafer stage top plate 12. The operation, function, effect, and thenecessity of retraction spaces 89 a and 89 b are all correspond to thoseof the sixth embodiment (FIG. 13).

FIG. 16 shows an example wherein the element having a positive rigidityis provided by a repulsion magnet 93 including a large magnet 93 a and asmall magnet 93 b, whose opposed surfaces have different areas. Themagnet 93 a is secured to the bottom face of the wafer stage top plate12 while the magnet 93 b is secured to the top face of the X stage topplate 11, wherein their faces to be opposed to each other have differentareas. With this arrangement, any vibration along the planeperpendicular to the supporting direction can be intercepted. Theremaining operation, function, effect, and the necessity of retractionspaces 89 a and 89 b all correspond to those of the sixth embodiment.

FIG. 17 is a front view of a further modified example of the sixthembodiment. The structural components used in this example are similarto those of the example of FIG. 15. As compared with the attractingmagnet 23 of telescopic structure used in the FIG. 15 example, in thisexample the magnet 23 does not have a telescopic structure but, rather,the magnet 23 is simply fixed to the wafer stage top plate 12. Also, adownward moving iron plate 94 is fixed to the flat coil 16 which isfixed to the top plate 11. As a result of this, while the retractionspace 89 is defined above the magnet 23 in the FIG. 15 example, in thisexample such space is not used. Further, while in the FIG. 15 examplethe magnet 23 produces a force for floating the stage top plate 12, inthis example the magnet 23 produces a weak force for pulling the topplate 12 downwardly. In place, the coil springs 95 function to supportthe weight of the wafer stage top plate 12. In this example, when thetop plate 12 retracts from the FIG. 17 state for the wafer placement,the flexure of the coil spring 95 increases. On the other hand, sincethe spacing between the magnet 23 and the iron plate 94 is reduced, theforce applied downwardly to the top plate 12 increases. Thus, withappropriate setting, the increase of force applied upwardly to the topplate 12 and the increase of force applied downwardly to the top plate12 can be cancelled.

As a result, even if the top plate 12 is retracted by a few millimetersfor wafer placement, heat generation at the linear motor can besuppressed and, thus, thermal deformation of the wafer stage top plate12 can be prevented, like the sixth embodiment shown in FIG. 13.

Further, in respect to the vibration transmission in the supportingdirection, cancellation of the spring constants is effective to improvethe vibration blocking performance in the supporting direction, like thesixth embodiment of FIG. 13.

Since the magnet 23 does not have a telescopic structure, only theretraction space is necessary at the gap side. The height as a whole canbe lowered.

In this example, in the state of FIG. 17, that is, in the state forexposure process, the spring constant of the coil spring 95 can easilybe set to be larger than the negative spring constant of the magnet 23.Once the setting is made so, in the FIG. 17 state (prepared for exposureprocess), with a shift in the supporting direction from the balancedposition, a resilience force operates in the supporting direction.Namely, a stable system wherein stability is produced automatically atthe balanced position, is assured. Thus, even if the power source of thelinear motor 4 is disconnected and the control becomes unattainable, itcan be held stationary at the balanced position. This is advantageous inrespect to the safety.

FIG. 18 is a front view of a further modified example to the FIG. 17example. In this example, in place of the coil spring 95, the elementhaving a positive rigidity is provided by repulsion magnets 97 (97 a, 97b) having different areas at their opposed faces. Like the FIG. 17example, the attraction magnet 23 is arranged to produce a force forpulling down the wafer stage top plate 12. The function and effect ofthis embodiment are the same as those of the FIG. 17 example.

Seventh Embodiment

FIGS. 19A, 19B and 19C show a fine-motion stage of a supporting systemaccording to a seventh embodiment of the present invention, whereinFIGS. 19A and 19B are front views, respectively, and FIG. 19C is anenlarged and exploded perspective view.

In order to place a wafer W on the fine-motion stage 1, a transfermechanism for transferring the wafer W from a hand to the fine-motionstage 1 is necessary. A portion of this mechanism is provided in thisembodiment by the fine-motion stage 1. In the supporting system of thisembodiment, in addition to the structure of FIG. 9 or 10, that is, theweight supporting system based on the attraction magnet 55 of telescopicstructure wherein a difference in size is set along a planeperpendicular to the attracting direction, there is an L-shaped leafspring 80 provided in parallel. Further, in consideration of thetransfer operation, there is a recess 88 which is formed at the top ofthe weight supporting system based on the attraction magnet 55 oftelescopic structure. In this case, while the weight is supported by theleaf spring 80, if the simple leaf spring 71 having an I-shaped sectionshown in FIG. 14 is used, it is rigid in the plane perpendicular to theflexure direction. It is not possible to block the vibration along theplane perpendicular to the supporting direction, only by use of thisspring.

In consideration of it, the L-shaped leaf spring 80 is used so that,when the top plate 12 shifts in a direction along the length of the flatcoil 16, no resilience force is applied in the shift direction. A pairof L-shaped leaf springs 80 are used. A base end is fixedly connected tothe coil 16 through a supporting member 72. The outside face of eachfree end is fixedly connected to the lower end of the corresponding yoke81, projected from the top plate 12 downwardly.

The Z drive suspension units 2 is disposed so that the direction inwhich the resilience force of the magnet 55 similar to that of FIG. 8and the L-shaped spring 80 does not apply is put along thecircumferential direction of the universal joint 6 shown in FIG. 8.

The attraction magnet 55 of telescopic structure having a difference insize in the direction of the length of the coil 16 as well as theL-shaped leaf spring 80 have, as has been described with reference tothe preceding embodiments, the weight supporting function and thevibration blocking function. Also in this embodiment, substantially thesame functions and effects as those of the preceding examples areattainable.

Here, duplicate use of the attraction magnet 55 and the L-shaped leafspring 80 having similar functions, will now be explained in detail. Inthe attracting magnet 55 of telescopic structure having a difference insize along a plane perpendicular to the attracting direction, inresponse to a shift of the magnet and the iron plate in the attractingdirection, a force opposite to the resilience force is produced. Namely,it has a negative rigidity. On the other hand, with the leaf spring 80,a resilience force operates against the displacement of the leaf spring80. Namely, it has a positive rigidity. Combining an element having anegative rigidity and an element having a positive rigidity provides animportant meaning, in the fine-motion stage which provides a portion ofthe function as the transfer mechanism. Also, the portion of thetransfer function which the fine-motion stage bears is the retractingfunction. Since they are substantially the same as those of the sixthembodiment shown in FIG. 13, description will be omitted.

Where the attraction magnet 55 with negative rigidity and the leafspring 80 with positive rigidity are used in combination, when the waferstage top plate 12 retracts by a few millimeters, from the state of FIG.19B to the state of FIG. 19C, the gap is expanded and the attractingforce of the magnet 55, that is, the floating force, is reduced. On theother hand, at the leaf spring 80, the flexure increases to enlarge thespring force and thus the floating force. Thus, through appropriatesetting, changes in force of them can be substantially cancelled.

As a result of this, even when the top plate 12 is retracted by a fewmillimeters for wafer placement, heat generation at the linear motor 4can be suppressed and, thus, thermal deformation of the top plate 12 canbe prevented. Further, in respect to the vibration transmission in thesupporting direction, cancellation of the spring constants is effectiveto improve the vibration blocking performance in the supportingdirection.

FIG. 20 shows a first modified example of the seventh embodiment of thepresent invention. In place of the leaf spring 80, the element having apositive rigidity is provided by a coil spring 101. The operation,function, effect, and the necessity of retraction spaces 89 a and 89 bare all correspond to those of the seventh embodiment (FIG. 19).

FIG. 21 shows a second modified example wherein the element having apositive rigidity is provided by a repulsion magnet 103 includingmagnets 93 a and 93 b, whose opposed surfaces have different areas. Therepulsion magnets are arranged to have a difference in area at theopposed faces. With this arrangement, any vibration along the planeperpendicular to the supporting direction can be intercepted. The sizedifference in the opposed faces may be set in every direction along theplane. However, if it is set specifically with respect to the directionalong the circumference of the universal joint 6, the vibration blockingperformance can be improved more. Alternatively, the difference in areacan be made smaller without degrading the vibration blocking function.The remaining operation, function, effect, and the necessity ofretraction spaces 89 a and 89 b all correspond to those of the sixthembodiment of FIG. 19.

FIG. 22 is a front view of a third modified example of the sixthembodiment. The structural components used in this example are similarto those of the example of FIG. 20. As compared with the attractingmagnet 55 of telescopic structure used in the FIG. 20 example, in thisexample the magnet 55 does not have a telescopic structure. Also, adownward moving iron plate 94 is simply fixed to the wafer stage topplate 12. Also, the magnet 55 is fixed, through a yoke 56, to the flatcoil 16 of the linear motor 4 which is fixed to the top plate 11. As aresult of this, while the retraction space 89 is defined above themagnet 55 in the first and second modified examples shown in FIGS. 20and 21, in this example such space is not used. Further, while in theFIG. 20 example the magnet 55 produces a force for floating the stagetop plate 12, in this example the magnet 55 produces a weak force forpulling the top plate 12 downwardly. In place, the coil springs 105function to support the weight of the wafer stage top plate 12.

When the top plate 12 retracts from the FIG. 22 state for the waferplacement, the flexure of the coil spring 105 increases. On the otherhand, since the spacing between the magnet 55 and the iron plate 94 isreduced, the force applied downwardly to the top plate 12 increases.Thus, with appropriate setting, the increase of force applied upwardlyto the top plate 12 and the increase of force applied downwardly to thetop plate 12 can be cancelled.

As a result, even if the top plate 12 is retracted by a few millimetersfor wafer placement, heat generation at the linear motor can besuppressed and, thus, thermal deformation of the wafer stage top plate12 can be prevented, like the seventh embodiment shown in FIG. 19.

Further, in respect to the vibration transmission in the supportingdirection, cancellation of the spring constants is effective to improvethe vibration blocking performance in the supporting direction, like theseventh embodiment of FIG. 19.

A large difference of this example over the seventh embodiment of FIG.19 is that, since the magnet 55 does not have a telescopic structure,only the retraction space is necessary at the gap side. The height as awhole can be lowered.

In this example, in the state of FIG. 22, that is, in the state forexposure process, the spring constant of the coil spring 105 can easilybe set to be larger than the negative spring constant of the magnet 55.Once the setting is made so, in the FIG. 22 state (prepared for exposureprocess), with a shift in the supporting direction from the balancedposition, a resilience force operates in the supporting direction.Namely, a stable system wherein stability is produced automatically atthe balanced position, is assured. Thus, even if the power source of thelinear motor 4 is disconnected and the control becomes unattainable, itcan be held stationary at the balanced position. This is advantageous inrespect to the safety.

FIG. 23 is a front view of a fourth modified example of the seventhembodiment, further modification being made to the example of FIG. 22.In this example, in place of the coil spring 105, the element having apositive rigidity is provided by repulsion magnets 107 (107 a, 107 b)having different areas at their opposed faces. Like the FIG. 22 example,the attraction magnet 55 and the iron plate 94 are arranged to produce aforce for pulling down the wafer stage top plate 12. The function andeffect of this embodiment are the same as those of the FIG. 22 example.

Here, comparison will be made in regard to the amount of heat generationby the linear motor 4 in the transfer procedure and to the stability atthe exposure position, between a type in which the attraction magnet 23has a telescopic structure and produces a floating force to the topplate 12 such as shown in FIGS. 1, 15 and 16, and a type in which themagnet 23 or 55 does not have a telescopic structure but it applies adownwardly pulling force to the top plate 12. Namely, the influence of atelescopic structure and non-telescopic structure to the heat generationat the linear motor 4 during the transfer process and the conditionsetting for stabilized exposure, will be considered.

FIG. 24A shows the characteristics, to a gap, of the spring force,magnet force, and a combined force of them, as the magnet 23 not havinga telescopic structure but applying a downward pulling force to the topplate 12, is set to be stabilized at the exposure position. The axis ofabscissa in FIG. 14A is the magnet gap, and the direction in which thegap increases corresponds to the direction in which the top plate 12shift upwardly. The axis of ordinate denotes the floating force. Thenegative direction along the axis of ordinate denotes the force formoving the top plate 12 downwardly. First, a force for floating the topplate 12 is continuously produced at the spring 95, and it is in theupper half region in the coordinate system of FIG. 24A. The spring forcechanges linearly in response to the change in gap or a shift of the topplate 12, and the force in the floating direction decreases in responseto the increase of the gap or to the upward shift of the top plate 12.Thus, in the region at the upper half of the coordinate system of FIG.24A, the spring force is illustrated by a straight line tiltedrightwardly downwardly.

The magnet 23 continuously produces a force for moving the top plate 12downwardly, and it is in the region at the lower half of the coordinatesystem of FIG. 24A. Also, the absolute value of the attracting forcechanges to the gap approximately in accordance with“1/(gap)<SUP>2</SUP>”. Thus, the attracting force is in the region atthe lower half of the coordinate system of FIG. 24A, and it isillustrated by a straight line tilted rightwardly upwardly.

For wafer transfer, the wafer stage top plate must be retracted. Thus,for the magnet gap, the following relation should be satisfied:“gap at exposure position”=“transfer stroke”+“gap at transfer position”Thus, in the coordinate system of FIG. 24A, the exposure position gap isat the right-hand side of the transfer position gap.

Also, in order to support the weight of the top plate 12 at the exposureposition, the relation“weight of top plate 12”=“spring force”+“magnet force”should be satisfied. In order to accomplish this relation, the springconstant of the spring 95 as well as the initial flexure at the exposureposition should satisfy the following relation:“spring constant”×“initial flexure”=“weight”−“magnet force at exposureposition” (sign of the magnet force is negative)The spring constant and the spring initial flexure at the exposureposition are set so as to be approximately equal to the weight.

For stabilization at the exposure position, as described with referenceto the example of FIG. 17, the absolute value of the changing rate, tothe gap, of the coil spring 95 at the exposure position should be set tobe larger than the absolute value of the changing rate, to the gap, ofthe magnet 23. In the case of spring, the changing rate to the gap isconstant regardless of the gap, and it corresponds to the tilt of thestraight line that represents the spring characteristic in FIG. 24.

On the other hand, the changing rate, to the gap, of the magnet force atthe exposure position corresponds to the tilt of a tangent of the magnetforce characteristic curve at the gap corresponding to the exposureposition.

Where the setting is made to satisfy the relation:“absolute value of tilt of straight line representing the springcharacteristic”>“absolute value of tilt of a tangent of magnet forcecharacteristic curve at gap corresponding to exposure position”Then, the changing rate of the combined force at the exposure position,to the gap, takes a negative value in the coordinate system of FIG. 24.As the gap increases or the top plate 12 shifts upwardly, the floatingforce decreases. As the gap decreases or the top plate 12 shiftsdownwardly, the floating force increases. Thus, the system is such thata resilience force applies in response to a gap change about the balanceposition. Even if the linear motor or the control system goes out oforder where the stage is at the balanced position, it can be kept there.The characteristic of the combined force of the spring force and magnetforce is illustrated by a thick line in FIG. 24A.

In this condition setting example, the following relation should besatisfied at the transfer position:“weight of top plate 12”=“spring force”+“magnet force”When this relation, that is, the balance at the transfer position andthe balance at the exposure position, is accomplished, at the transferposition the changing rate (tilt of tangent) of the combined force(spring force plus magnet force) to the gap is tilted rightwardlyupwardly. Thus, at the transfer position, without the control of linearmotor 4, the system becomes unstable. In this manner, the conditionsetting for that the weight and the combined force are balanced at theexposure position and the transfer position, and additionally that it isstabilized at the exposure station, is very advantageous in respect tothe heat generation by the linear motor 4, while there may be a smallrisk when the linear motor goes out of order at the transfer position.

The amount P of heat generation of the linear motor 4 during thetransfer process can be approximated by:P=Σr(i(y))² Δtwhere r is the resistance of the linear motor 4, i(y) is the electriccurrent as the top plate 12 is at the position y, and Δt is the time inwhich the plate is about that position.

In the transfer procedure, the wafer stage top plate 12 is kept at thetransfer position in most period of time. On its way, it merely passesso that the time there is very short. If therefore the setting is madeso that the combined force and the weight are balanced at the transferposition, i(y) becomes substantially zero where the value Δt is large(about the transfer position). On the way to the transfer, since the topplate passes quickly the location where Δt is large, such that Δt issmall and the product of i and Δt can continuously be held small. Intotal, the amount P of heat generation can be made small.

Also, by balancing the weight and the combined force at the exposureposition, after the transfer and during the exposure process to thewafer W, the amount of heat generation of the linear motor 4 can be madesubstantially zero.

FIG. 24B shows an example wherein the combined force and the weight arebalanced at the exposure position, and wherein the magnitude relation ofthe changing rate of the spring characteristic and the magnetcharacteristic at the exposure position is set so as to provide a systembeing stable at the exposure position; whereas, since a magnet in whichthe absolute value of the changing rate of the magnet characteristic isgenerally small is used, the balancing is not attained at the transferposition. Any imbalance must be compensated by the linear motor 4. Inthis example, since the electric current of the linear motor 4 becomesnot zero at about the transfer position where the stay time is long, theamount of heat generation slightly increases as compared with the FIG.24A example. However, if the amount of heat generation is small, it isnot always necessary that the combined force is exactly balanced withthe weight. The same applies to the exposure position. If the balanceerror is small, heat generation does not raise a problem.

On the other hand, FIG. 25 shows an example of unpreferable setting.More specifically, FIG. 25 shows an example wherein, although thecombined force and the weight are balanced at the exposure position,since the magnitude relation of the changing rate of the springcharacteristic and the magnet characteristic is set so that the systemis unstable at the exposure position, the weight and the combined forcedo not balance at a gap smaller than the exposure position. In thiscase, at about the transfer position where the stay time is long, theamount of imbalance between the combined force and the weight, namely,the current of the linear motor 4, becomes largest, such that the heatgeneration increases very much.

At the moment that the condition setting for providing an unstablesystem at the exposure position is done, the combined force and theweight can balance only in the state that the wafer stage top plate 12shifts by a gap larger than the exposure position, namely, it shiftsbeyond the exposure position. This position is in the opposite directionto the wafer transfer and, therefore, any balance does not have ameaning. The condition setting for providing a system being unstable atthe exposure position, in the type shown in FIG. 17, is undesirablesince the risk upon any disorder of the linear motor at the exposureposition becomes large and also the heat generation increases.

In summary, in the type in which the attracting magnet 23 such as shownin FIG. 17 has a non-telescopic structure, the condition setting withwhich, at the exposure position, the combined force and the weight arebalanced and the system is stable there, is necessary first.Additionally, the condition should preferably be set so that thecombined force and the weight are balanced at the transfer position.

If the condition is to be relieved slightly, it is desired that thecombined force and the weight are balanced at the exposure position andthat the characteristic of the combined force at the exposure positionis stable (the tangent of the combined force at the exposure position istilted rightwardly downwardly in the coordinate system of FIG. 24A or24B), and also that the combined force and the weight are approximatelybalanced at the transfer position.

If the condition is to be relieved more, it is desirable that thecombined force and the weight are balanced at about the exposureposition and the transfer position, and that the characteristic of thecombined force at the exposure position is stable (the tangent of thecombined force at the exposure position is tilted rightwardly downwardlyin the coordinate system shown in FIG. 24 or 25).

FIG. 26 shows characteristics of the spring force, the magnet force andthe combined force of them, to a gap, where the attraction magnet 23shown in FIG. 15 has a telescopic structure so that it applies afloating force to the wafer stage top plate 12, and where the conditionis set so that the system is unstable at the exposure position.

The axis of abscissa in FIG. 26 depicts the gap, and the direction inwhich the gap increases corresponds to the direction in which the topplate 12 shifts downwardly. The axis of ordinate denotes the floatingforce. First, a force for floating the top plate 12 is continuouslyproduced at the spring 91, and it is in the upper half region in thecoordinate system of FIG. 26. The spring force of the coil spring 91changes linearly in response to the change in gap or a shift of the topplate 12, and the force in the floating direction decreases in responseto the increase of the gap or to the upward shift of the top plate 12.Thus, in the region at the upper half of the coordinate system of FIG.26, the spring force is illustrated by a straight line tiltedrightwardly upwardly.

The magnet 23 continuously produces a force for floating the top plate12, and it is in the region at the upper half of the coordinate systemof FIG. 26. Also, the absolute value of the attracting force changes tothe gap approximately in accordance with “1/(gap)²”. Thus, theattracting force is in the region at the upper half of the coordinatesystem of FIG. 26, and it is illustrated by a straight line tiltedrightwardly downwardly.

For wafer transfer, the wafer stage top plate must be retracted. Thus,for the magnet gap, the following relation should be satisfied:“gap at transfer position”=“transfer stroke”+“gap at exposure position”Thus, in the coordinate system of FIG. 26, the transfer position gap isat the right-hand side of the exposure position gap.

Also, in order to support the weight of the top plate 12 at the exposureposition, the relation“weight of top plate 12”=“spring force”+“magnet force”.should be satisfied. In order to accomplish this relation, the springconstant of the spring 91 as well as the initial flexure at the exposureposition should satisfy the following relation:“spring constant”×“initial flexure”=“weight”−“magnet force at exposureposition” (sign of the magnet force is positive)The spring constant and the spring initial flexure at the exposureposition are set so as to be approximately equal to the weight.

Also, FIG. 26 shows a case wherein a system being unstable at theexposure position is provided. To this end, the absolute value of thechanging rate, to the gap, of the coil spring 91 at the exposureposition should be set to be smaller than the absolute value of thechanging rate, to the gap, of the magnet 23. In the case of spring 91,the changing rate to the gap is constant regardless of the gap, and itcorresponds to the tilt of the straight line that represents the springcharacteristic in FIG. 26.

On the other hand, the changing rate, to the gap, of the magnet force atthe exposure position corresponds to the tilt of a tangent of the magnetforce characteristic curve at the gap corresponding to the exposureposition.

Where the setting is made to satisfy the relation:“absolute value of tilt of straight line representing the springcharacteristic”<“absolute value of tilt of a tangent of magnet forcecharacteristic curve at gap corresponding to exposure position”Then, the changing rate of the combined force at the exposure position,to the gap, takes a negative value in the coordinate system of FIG. 26.As the gap increases or the top plate 12 shifts downwardly, the floatingforce decreases. As the gap decreases or the top plate 12 shiftsupwardly, the floating force increases. Thus, the system is such that aresilience force applies in response to a gap change about the balanceposition.

The characteristic of the combined force of the spring force and magnetforce is illustrated by a thick line in FIG. 26.

In this condition setting example, the following relation should besatisfied at the transfer position:“weight of top plate 12”=“spring force”+“magnet force”When this relation, that is, the balance at the transfer position andthe balance at the exposure position, is accomplished, at the transferposition the changing rate (tilt of tangent) of the combined force(spring force plus magnet force) to the gap is tilted rightwardlyupwardly. Thus, at the transfer position, the system becomes stable. Inthis manner, the condition setting for that the weight and the combinedforce are balanced at the exposure position and the transfer position,and additionally that it is unstable at the exposure station, is veryadvantageous in respect to the heat generation by the linear motor 4,while there may be a small risk when the linear motor goes out of orderat the exposure position.

The amount P of heat generation of the linear motor 4 during thetransfer process can be approximated by:P=Σr(i(y))² Δtwhere r is the resistance of the linear motor 4, i(y) is the electriccurrent as the top plate 12 is at the position y, and Δt is the time inwhich the plate is present about that position.

In the transfer procedure, the wafer stage top plate 12 is kept at thetransfer position in most period of time. On its way, it merely passesso that the time there is very short. If therefore the setting is madeso that the combined force and the weight are balanced at the transferposition, i(y) becomes substantially zero where the value Δt is large(about the transfer position). On the way to the transfer, since the topplate passes quickly the location where t is large, such that Δt issmall and the product of i and Δt can continuously be held small. Intotal, the amount P of heat generation can be made small.

Also, by balancing the weight and the combined force at the exposureposition, after the transfer and during the exposure process to thewafer W, the amount of heat generation of the linear motor 4 can be madesubstantially zero.

On the other hand, FIG. 27 shows an example of unpreferable setting.More specifically, FIG. 27 shows an example wherein, although thecombined force and the weight are balanced at the exposure position,since the magnitude relation of the changing rate of the springcharacteristic and the magnet characteristic is set so that the systemis stable at the exposure position, the weight and the combined force donot balance at a gap smaller than the exposure position. In this case,at about the transfer position where the stay time is long, the amountof imbalance between the combined force and the weight, namely, thecurrent of the linear motor 4, becomes largest, such that the heatgeneration increases very much.

At the moment that the condition setting for providing a stable systemat the exposure position is done, the combined force and the weight canbalance only in the state that the wafer stage top plate 12 shifts by agap smaller than the exposure position, namely, it shifts upwardlybeyond the exposure position. This position is in the opposite directionto the wafer transfer and, therefore, any balance does not have ameaning. Practically, the gap at the exposure position is small, so thatthe magnets may physically contact with each other and, therefore, thebalanced state is not attainable. The condition setting for providing asystem being stable at the exposure position, in the type shown in FIG.15, is undesirable since the risk upon any disorder of the linear motorat the exposure position becomes large and also the heat generationincreases.

In summary, in the type in which the attracting magnet 23 such as shownin FIG. 15 has a telescopic structure, the condition setting with which,at the exposure position, the combined force and the weight are balancedand the system is unstable there, is necessary first. Additionally, thecondition should preferably be set so that the combined force and theweight are balanced at the transfer position.

If the condition is to be relieved slightly, it is desired that thecombined force and the weight are balanced at the exposure position andthat the characteristic of the combined force at the exposure positionis unstable (the tangent of the combined force at the exposure positionis tilted rightwardly downwardly in the coordinate system of FIG. 26 or27), and also that the combined force and the weight are approximatelybalanced at the transfer position.

If the condition is to be relieved more, it is desirable that thecombined force and the weight are balanced at about the exposureposition and the transfer position, and that the characteristic of thecombined force at the exposure position is unstable (the tangent of thecombined force at the exposure position is tilted rightwardly downwardlyin the coordinate system shown in FIG. 26 or 27).

Comparing the attraction magnet 23 to be provided in parallel to thespring element, in respect to the amount of heat generation in thelinear motor 4 such as described above, as for the type in which atelescopic structure is used and a floating force is applied to thewafer stage top plate 12, in order to make the amount of heat generationsmall, the system should be stable at the exposure position. In the typewherein a non-telescopic structure is used and a force in the gravitydirection is applied to the top plate 12, in order to make the heatgeneration small, the system should be stable at the exposure position.Being stable at the exposure position is, of course, desirable.

Thus, in the type in which a telescopic structure is used and a floatingforce is applied to the top plate 12, it is difficult to assure both thestability at the exposure position and the small heat generation of thelinear motor 4. With the type in which a non-telescopic structure isused and a force in the gravity direction is applied to the top plate12, both the stability at the exposure position and the small heatgeneration can be accomplished. Thus, the latter may be preferable inthis respect.

The present invention is not limited to the embodiments and examplesdescribed above, and various modifications are possible. For example,the attracting magnet 23 of telescopic structure in the sixth embodimentof FIG. 13 may be omitted, and the weight supporting mechanism for thetop plate 12 may be provided only by use of the leaf spring 71. Further,the magnet 55 of telescopic structure of the seventh embodiment shown inFIG. 19 may be omitted, and the weight supporting mechanism may beprovided only by the L-shaped leaf spring 80.

Embodiment of Device Manufacturing Method

Next, an embodiment of a semiconductor device manufacturing method whichuses an exposure apparatus with a supporting system such as describedabove, will be explained.

FIG. 31 is a flow chart of procedure for manufacture of microdevicessuch as semiconductor chips (e.g. ICs or LSIs), liquid crystal panels,CCDs, for example.

Step 1 is a design process for designing a circuit of a semiconductordevice. Step 2 is a process for making a mask on the basis of thecircuit pattern design. Step 3 is a process for preparing a wafer byusing a material such as silicon. Step 4 is a wafer process (called apre-process) wherein, by using the so prepared mask and wafer, circuitsare practically formed on the wafer through lithography. Step 5subsequent to this is an assembling step (called a post-process) whereinthe wafer having been processed by step 4 is formed into semiconductorchips. This step includes an assembling (dicing and bonding) process anda packaging (chip sealing) process. Step 6 is an inspection step whereinoperation check, durability check and so on for the semiconductordevices provided by step 5, are carried out. With these processes,semiconductor devices are completed and they are shipped (step 7).

FIG. 32 is a flow chart showing details of the wafer process.

Step 11 is an oxidation process for oxidizing the surface of a wafer.Step 12 is a CVD process for forming an insulating film on the wafersurface. Step 13 is an electrode forming process for forming electrodesupon the wafer by vapor deposition. Step 14 is an ion implanting processfor implanting ions to the wafer. Step 15 is a resist process forapplying a resist (photosensitive material) to the wafer. Step 16 is anexposure process for printing, by exposure, the circuit pattern of themask on the wafer through the exposure apparatus described above. Step17 is a developing process for developing the exposed wafer. Step 18 isan etching process for removing portions other than the developed resistimage. Step 19 is a resist separation process for separating the resistmaterial remaining on the wafer after being subjected to the etchingprocess. By repeating these processes, circuit patterns are superposedlyformed on the wafer.

With these processes, high density microdevices can be manufactured.

While the invention has been described with reference to the structuresdisclosed herein, it is not confined to the details set forth and thisapplication is intended to cover such modifications or changes as maycome within the purposes of the improvements or the scope of thefollowing claims.

1-36. (canceled)
 37. An exposure apparatus comprising: carrying meansfor carrying thereon a substrate; and supporting means being movable ina gravity direction while supporting said carrying means, wherein,within a movement range in the gravity direction of said supportingmeans, there are two points where a supporting force for said carryingmeans and a weight of said carrying means, having the substrate carriedthereon, are balanced.